"Please create a group first"?

i've installed the og_actions_v2.tar_.gz and that seems to work fine, but only to a certain extent.
I'd like to activate the "add node to the specified group ..." action, but every time i try to do so, I am prompted to "Please create a group first." I have meanwhile created a new group, but that doesn't change this result. on the "configure an advanced option" page, which is where i am prompted to create a group, I get the warning warning: array_merge() [function.array-merge]: Argument #2 is not an array in <strong>example.com</strong>\modules\actions\actions.module on line 339. I am most probably overlooking something, but I honestly don't understand what is going wrong. could someone please find time to explain?

kindly yours,

Joris